JP2017141606A - Construction machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a construction machine capable of highly accurately controlling a hydraulic fluid temperature, even if it has a cooler relief valve.SOLUTION: An extra-large type hydraulic shovel on the present invention comprises a fan controller 35 for determining a measured temperature difference ΔT being a difference between the inlet temperature To1 of an oil cooler 20 detected by a second temperature sensor 31 and the outlet temperature To2 of the oil cooler 20 detected by a third temperature sensor 32, when the hydraulic fluid temperature (t) detected by a first temperature sensor 30 is a lower limit value gmin or more of an optimal hydraulic fluid temperature range G, by determining a temperature difference arithmetic operation value ΔTA of an inlet-outlet of the oil cooler 20 from the hydraulic fluid temperature (t) of a suction pipe of a third variable capacity hydraulic pump 13 detected by the first temperature sensor 30, and can lower a rotating speed NB of a cooling fan 22 more than the highest rotating speed N-Hi by control of the fan controller 35 based on the measured temperature difference ΔT and the temperature difference arithmetic operation value ΔTA.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a construction machine having an oil cooler that cools hydraulic oil and a cooling fan that generates wind that cools the oil cooler.

  Construction machinery, for example, ultra-large hydraulic excavators, drives actuators such as hydraulic cylinders and hydraulic motors via directional control valves, cools hydraulic oil by passing the return oil through an oil cooler and flowing it to a tank. . Since the oil cooler has a large pressure loss, it is not possible to pass all the hydraulic oil through the oil cooler when the flow rate of return oil is large. In such a case, the cooler relief valve is actuated to cause an excessive flow rate to flow into the tank, thereby preventing the oil cooler inlet from becoming a high pressure.

  In the ultra-large hydraulic excavator, the return oil of the turning motor that performs the turning operation is directly returned to the tank without passing through the oil cooler. This is because the return oil of the swing motor has a large flow rate, the inlet of the oil cooler becomes high pressure, and if the return oil of the swing motor is guided to the oil cooler, the life of the oil cooler is shortened.

  Conventionally, the number of revolutions of the cooling fan that generates the air that cools the oil cooler is controlled based on the hydraulic oil temperature detected by one temperature sensor provided in the suction pipe that connects the tank and the hydraulic pump.

  By the way, when a construction machine having a cooler relief valve is operated in an extremely cold region, overheating of the hydraulic oil may occur although it is extremely rare. This is because the hydraulic oil viscosity in the oil cooler increases due to the overcooling of the oil cooler, and the hydraulic oil does not easily flow into the oil cooler. If it will be in this state, the high temperature hydraulic fluid which returned from each actuator will return to a tank directly from a cooler relief valve. Therefore, the hydraulic oil temperature gradually increases, and the rotational speed of the cooling fan of the oil cooler gradually increases accordingly. However, the oil cooler continues to be in a state where hydraulic fluid cannot flow due to overcooling. Such a vicious cycle results in overheating of the hydraulic oil.

  Patent Document 1 discloses a temperature control device for hydraulic oil such as construction machinery. The prior art disclosed in this Patent Document 1 installs pressure sensors upstream and downstream of the oil cooler, calculates the flow rate of the oil cooler from the upstream and downstream pressure differences detected by these pressure sensors, The number of rotations of the cooling fan that cools the oil cooler is controlled.

JP 2014-167262 A

  In a construction machine having a cooler relief valve such as an ultra-large hydraulic excavator, when adopting the prior art disclosed in Patent Document 1, return oil from the actuator is provided with an oil cooler inlet and a cooler relief valve. Will be diverted to the other pipe. For this reason, the inlet pressure of the oil cooler becomes unstable. Therefore, the pressure difference between the upstream and downstream sides of the oil cooler detected by each of the pressure sensors becomes basically unstable, and there is a possibility that the control accuracy of the hydraulic oil temperature based on this pressure difference is lowered.

  In order to solve the above problems, an object of the present invention is to provide a construction machine that can perform highly accurate hydraulic oil temperature control even if it has a cooler relief valve.

  In order to solve the above-described problems, a construction machine according to the present invention includes a main body, a work device attached to the main body, a plurality of actuators including an actuator that operates the work device, and an operation device that operates these actuators. An engine mounted on the main body, a variable displacement hydraulic pump driven by the engine, an oil cooler that cools return oil from the actuator, a cooling fan that generates wind that cools the oil cooler, A fan motor for operating a cooling fan; a variable capacity fan pump for driving the fan motor; and a pipe line connecting the inlet side pipe and the tank of the oil cooler, and an excess of the inlet side pipe In a construction machine having a cooler relief valve for allowing a flow rate to escape to the tank, the variable displacement hydraulic pump A first temperature sensor for detecting the hydraulic oil temperature of the suction pipe, a second temperature sensor for detecting the inlet temperature of the oil cooler, a third temperature sensor for detecting the outlet temperature of the oil cooler, and an operation amount of the operating device The oil cooler inlet and outlet according to the engine speed, the discharge pressure of the variable displacement hydraulic pump, the hydraulic oil temperature of the suction pipe detected by the first temperature sensor, and the cooling fan speed , And when the hydraulic oil temperature of the suction pipe detected by the first temperature sensor is equal to or higher than a lower limit value of a preset optimum hydraulic oil temperature range, the second temperature sensor detects The measured temperature difference, which is the difference between the oil cooler inlet temperature and the oil cooler outlet temperature detected by the third temperature sensor, is calculated based on the calculation result. A fan controller for controlling the capacity of the fan pump, wherein the fan controller sets a correlation between the hydraulic oil temperature of the suction pipe and the number of rotations of the cooling fan, and the measured temperature difference. A second control table that sets a correlation between the difference between the temperature difference calculation value and the number of rotations of the cooling fan, and the correlation set in the first control table is an operation of the suction pipe When the oil temperature is lower than the lower limit value of the optimum hydraulic oil temperature range, the number of rotations of the cooling fan is the minimum number of rotations according to the drive state of the variable displacement hydraulic pump whose capacity is controlled to the minimum discharge amount. When the hydraulic oil temperature of the suction pipe is higher than the upper limit value of the optimum hydraulic oil temperature range, the rotation speed of the cooling fan is maintained at the maximum rotation speed, and the suction While the hydraulic oil temperature of the suction pipe is not less than the lower limit value and not more than the upper limit value of the optimum hydraulic oil temperature range, the number of rotations of the cooling fan gradually increases as the hydraulic oil temperature of the suction pipe increases. The correlation set in the second control table is such that when the difference between the measured temperature difference and the temperature difference calculation value is smaller than a lower limit threshold, the rotation speed of the cooling fan is set to the maximum rotation. When the difference between the measured temperature difference and the calculated temperature difference is equal to or greater than the lower limit threshold, the number of rotations of the cooling fan is gradually increased as the difference between the measured temperature difference and the calculated temperature difference increases. It is characterized by low correlation.

  The construction machine according to the present invention detects the hydraulic oil temperature of the suction pipe of the variable displacement hydraulic pump detected by the first temperature sensor, the inlet temperature of the oil cooler detected by the second temperature sensor, and the third temperature sensor. Even with a cooler relief valve by a fan controller that performs processing according to the outlet temperature of the oil cooler, it is not affected by fluctuations in the pressure difference between the upstream and downstream of the oil cooler as in the past. Highly accurate hydraulic fluid temperature control can be performed. That is, in the one having the cooler relief valve, overcooling of the oil cooler can be prevented, and overheating of the hydraulic oil resulting from the overcooling of the oil cooler can be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view showing a very large hydraulic excavator constituting a first embodiment of a construction machine according to the present invention. It is a circuit diagram which shows the principal part structure of the hydraulic drive device with which 1st Embodiment is equipped. It is a figure which shows the 1st control table set with the fan controller with which the hydraulic drive unit shown in FIG. 2 is equipped. It is a figure which shows the 2nd control table set with the fan controller with which the hydraulic drive apparatus shown in FIG. 2 is equipped. It is a flowchart which shows the process sequence in the fan controller with which the hydraulic drive apparatus shown in FIG. 2 is equipped. It is a circuit diagram which shows the principal part structure of the hydraulic drive apparatus with which 2nd Embodiment of this invention is equipped.

  Embodiments of a construction machine according to the present invention will be described below with reference to the drawings.

  As shown in FIG. 1, the first embodiment of the construction machine according to the present invention is configured by, for example, an ultra-large hydraulic excavator. The super-large hydraulic excavator includes a traveling body 1, a revolving body 2 that is disposed on the traveling body 1 and constitutes a main body, and a work device 3 that is attached to the revolving body 2 and performs excavation of earth and sand. ing.

  The work device 3 includes a boom 4 attached to the swing body 2 so as to be rotatable in the vertical direction, a boom cylinder 4a for operating the boom 4, an arm 5 attached to the tip of the boom 4 so as to be rotatable in the vertical direction, and An arm cylinder 5 a that operates the arm 5, a bucket 6 that is rotatably attached to the tip of the arm 5 and a bucket cylinder 6 a that operates the bucket 6 are included.

  Each of the boom cylinder 4a, the arm cylinder 5a, and the bucket cylinder 6a constitutes a hydraulic cylinder. A plurality of hydraulic cylinders, a traveling motor (not shown), a turning motor 19 shown in FIG. The actuator is configured.

  Further, in the first embodiment, an operation device (not shown) for operating each of the actuators, an engine 10 shown in FIG. 2 mounted on the revolving structure 2, and a variable displacement hydraulic pump driven by the engine 10, for example, a first variable displacement A hydraulic pump 11, a second variable displacement hydraulic pump 12, and a third variable displacement hydraulic pump 13 are provided. Although not shown, the engine 10 is provided with a rotational speed sensor for detecting the engine rotational speed Ne.

  Further, as shown in FIG. 2, the flow of the pressure oil connected to the first variable displacement hydraulic pump 11 and supplied to the hydraulic cylinder 15 generally showing the boom cylinder 4a, the arm cylinder 5a, and the bucket cylinder 6a described above. A first directional control valve group 16 including a directional control valve for controlling the directional control valve, a second directional control valve group 17 connected to the second variable displacement hydraulic pump 12, and a third variable displacement hydraulic pump 13. And a third directional control valve group 18 including a directional control valve for controlling the flow of the pressure oil supplied to the above-described turning motor 19 for turning 2.

  In the first embodiment, an oil cooler 20 that cools the return oil from the actuator, a cooling fan 22 that generates air to cool the oil cooler 20, a fan motor 23 that operates the cooling fan 22, For example, a variable displacement fan pump 14 that operates in synchronization with the third variable displacement hydraulic pump 13 and discharges the pressure oil that drives the fan motor 23 is provided. The oil cooler 20 is provided with a temperature sensor (not shown) that detects the oil cooler air inlet temperature Toa.

  A cooler relief valve 21 that allows the excess flow rate in the inlet side pipe 36 to escape to the tank 37 is disposed in a pipe line 38 that connects the inlet side pipe line 36 of the oil cooler 20 and the tank 37.

  In the first embodiment, the first temperature sensor 30 that detects the hydraulic oil temperature t of the suction pipe of the third variable displacement hydraulic pump 13, the second temperature sensor 31 that detects the inlet temperature To1 of the oil cooler 20, and the oil And a third temperature sensor 32 that detects an outlet temperature To2 of the cooler 20.

  Further, in the first embodiment, in addition to the first temperature sensor 30, the second temperature sensor 31, and the third temperature sensor 32, a rotation speed sensor (not shown) that detects the rotation speed Ne of the engine 10 and an operation amount La of the operation device are detected. An operation amount detection device (not shown), a temperature sensor for detecting the above-described oil cooler air inlet temperature Toa, and the like are connected, and a fan controller 35 that performs various control processes is provided.

  The fan controller 35 includes an operation amount La of an operation amount detection device (not shown), a rotational speed Ne of the engine 10, a discharge pressure Po of a corresponding variable displacement hydraulic pump among the variable displacement hydraulic pumps 11 to 13, and a first temperature sensor 30. In accordance with the hydraulic oil temperature t of the suction pipe detected in step S4, the rotational speed NA of the cooling fan 22, etc., a calculation for obtaining a temperature difference calculation value ΔTA at the inlet / outlet of the oil cooler 20 is performed.

  Further, the fan controller 35 uses the second temperature sensor 31 when the hydraulic oil temperature t of the suction pipe detected by the first temperature sensor 30 is equal to or higher than the lower limit value gmin of the optimum hydraulic oil temperature range G shown in FIG. Calculation is performed to obtain an actually measured temperature difference ΔT, which is a difference between the detected inlet temperature To1 of the oil cooler 20 and the outlet temperature To2 of the oil cooler 20 detected by the third temperature sensor 32.

  Furthermore, the fan controller 35 sets the rotational speed NB of the cooling fan 22 to the maximum rotational speed when the difference (ΔT−ΔTA) between the actually measured temperature difference ΔT and the temperature difference calculation value ΔTA shown in FIG. The capacity of the fan pump 14 is controlled so as to be changed to be lower than N-Hi. For example, when the difference (ΔT−ΔTA) between the actually measured temperature difference ΔT and the temperature difference calculation value ΔTA is greater than the upper limit value Δtm, the fan controller 35 controls the rotational speed NB of the cooling fan 22 to the minimum rotational speed N-Lo. Perform the process.

  That is, the fan controller 35 sets the correlation between the hydraulic oil temperature t of the suction pipe of the third variable displacement hydraulic pump 13 and the rotational speed NA of the cooling fan 22 and the measured temperature difference ΔT. And a second control table shown in FIG. 4 for setting a correlation between the difference (ΔT−ΔTA) between the temperature difference calculation value ΔTA and the rotational speed NB of the cooling fan 22.

  The correlation set in the first control table shown in FIG. 3 indicates that when the hydraulic oil temperature t of the suction pipe is lower than the lower limit value gmin of the optimal hydraulic oil temperature range G, the rotational speed NA of the cooling fan 22 is Is kept at the minimum rotation speed N-Lo corresponding to the driving state of the third variable displacement hydraulic pump 13 controlled to the minimum discharge amount, and the hydraulic oil temperature t of the suction pipe is from the upper limit value gmax of the optimal hydraulic oil temperature range G. Is higher, the rotational speed NA of the cooling fan 22 is maintained at the maximum rotational speed N-Hi, and the hydraulic oil temperature t of the suction pipe is between the lower limit value gmin and the upper limit value gmax of the optimal hydraulic oil temperature range G, The correlation is such that the rotational speed NA of the cooling fan 22 is gradually increased as the hydraulic oil temperature t of the suction pipe increases.

  The correlation set in the second control table shown in FIG. 4 is that when the difference (ΔT−ΔTA) between the measured temperature difference ΔT and the temperature difference calculation value ΔTA is smaller than the lower limit threshold Δts, the rotational speed NB of the cooling fan 22 Is maintained at the maximum rotational speed N-Hi, and the difference between the measured temperature difference ΔT and the temperature difference calculated value ΔTA (ΔT−ΔTA) is equal to or greater than the lower limit threshold Δts, As ΔT−ΔTA) increases, the rotational speed NB of the cooling fan 22 is gradually changed to be lower than the maximum rotational speed N-Hi.

  In the first embodiment, as described above, when the difference (ΔT−ΔTA) between the actually measured temperature difference ΔT and the temperature difference calculation value ΔTA is larger than the upper limit threshold value Δtm, the rotational speed NB of the cooling fan 22 In the minimum rotation speed N-Lo.

  Processing operations performed by the fan controller 35 provided in the first embodiment configured as described above will be described with reference to FIG.

[Step S1] When the engine key is turned on, it is determined whether or not the rotational speed Ne of the engine 10 has been input based on a signal from a rotational speed sensor (not shown) attached to the engine 10. When it is determined that the rotational speed Ne of the engine 10 has been input, the process proceeds to step S2.

[Step S2] Based on a signal from an operation amount detection device (not shown) that detects the operation amount La of the operation device that operates the hydraulic cylinder 15, it is determined whether or not the operation device that operates the hydraulic cylinder 15 has been operated. When it is determined that the corresponding operating device has been operated, the process proceeds to step S3.

[Step S3] Based on the operation amount La from the operation amount detection device (not shown), the engine speed Ne, the discharge pressure Po of the variable displacement hydraulic pumps 11 to 13, and the preset pump control table, the calculated pump discharge flow rate Qp is calculated, and the process proceeds to step S4.

[Step S4] A calculated return flow rate Qr is calculated based on the calculated pump discharge flow rate Qp, each actuator operating pressure, and the hydraulic oil temperature t of the suction pipe. This calculated return flow rate Qr, the passage pressure loss of the oil cooler 20, and the cooler The calculated oil cooler passage flow rate Qo is calculated from the pressure balance of the relief valve 21, and the process proceeds to step S5.

[Step S5] Based on the calculated oil cooler passage flow rate Qo, the oil cooler air inlet temperature Toa, and the rotational speed NA of the cooling fan 22, a temperature difference calculation value ΔTA is calculated, and the process proceeds to step S6.

[Step S6] It is determined whether the hydraulic oil temperature t of the suction pipe is lower than the lower limit value gmin of the optimal hydraulic oil temperature range G shown in FIG. When it is determined that the value is lower than the lower limit value gmin, the process proceeds to step S7. When it is determined that the value is equal to or greater than the lower limit gmin, the process proceeds to step S8.

[Step S7] The capacity of the fan pump 14 is controlled so that the rotational speed NA of the cooling fan 22 becomes the minimum rotational speed N-Lo, and the process returns to Step S6.

[Step S8] An actually measured temperature difference ΔT that is a difference between the inlet temperature To1 detected by the second temperature sensor 31 and the outlet temperature To2 detected by the third temperature sensor 32 is obtained, and the process proceeds to Step S9.

[Step S9] It is determined whether the difference (ΔT−ΔTA) between the actually measured temperature difference ΔT and the temperature difference calculation value ΔTA is smaller than the lower limit threshold Δts of the second control table. When it is not smaller than the lower limit threshold Δts, that is, when it is determined to be equal to or higher than the lower limit threshold Δts, the oil cooler 20 may be overcooled, and the process proceeds to step S10. When it is determined that it is smaller than the lower limit threshold value Δts, the oil cooler 20 is in a state where there is no possibility of overcooling, and the process proceeds to step S11.

[Step S10] The rotational speed NB of the cooling fan 22 is calculated based on the second control table of FIG. At this time, in order to reduce the rotational speed NB of the cooling fan 22 below the maximum rotational speed N-Hi, the capacity of the fan pump 14 is made smaller than before, and the rotational speed of the fan motor 23 is lowered accordingly. Control and return to step S8. With this control, the air volume per unit time given to the cooling fan 22 is reduced, and cooling of the cooling fan 22 is suppressed.

[Step S11] Based on the first control table shown in FIG. 3, the capacity of the fan pump 14 is controlled so that the rotational speed NA of the cooling fan 22 corresponds to the hydraulic oil temperature t of the suction pipe. move on.

[Step S12] It is determined whether the engine key is OFF. When the engine key is not OFF, the process returns to step S1, and the same processing as described above is continued. When the engine key is OFF, the process of the fan controller 35 is terminated.

  Although omitted in the above-described flowchart, the fan controller 35 determines whether or not the difference (ΔT−ΔTA) between the measured temperature difference ΔT and the temperature difference calculation value ΔTA is larger than the upper limit threshold Δtm after step S11. When the determination is made and it is determined that the rotation speed is large, processing for controlling the capacity of the fan pump 14 is performed so that the rotation speed NB of the cooling fan 22 becomes the minimum rotation speed N-Lo.

  According to the super large hydraulic excavator according to the first embodiment configured as described above, the hydraulic oil temperature t of the suction pipe of the third variable displacement hydraulic pump 13 detected by the first temperature sensor 30 as described above, The cooler relief valve 21 is operated by a fan controller 35 that performs processing according to the inlet temperature To1 of the oil cooler 20 detected by the second temperature sensor 31 and the outlet temperature To2 of the oil cooler 20 detected by the third temperature sensor 32. Even if it has, it can control the hydraulic oil temperature t with high precision, without being influenced by the fluctuation | variation of the pressure difference of the upstream of the oil cooler 20, and a downstream. That is, in the one having the cooler relief valve 21, overcooling of the oil cooler 20 can be prevented, and overheating of the hydraulic oil resulting from overcooling of the oil cooler 20 can be prevented.

  FIG. 6 is a circuit diagram showing a main configuration of a hydraulic drive device provided in the second embodiment of the present invention. For example, the second embodiment of the present invention is configured by an ultra-large hydraulic excavator similar to that shown in FIG.

  The second embodiment of the present invention includes a stop device that stops the rotation of the cooling fan 22. The fan controller 35 controls the operation of the aforementioned stop device so as to stop the cooling fan 22 when the hydraulic oil temperature t of the suction pipe is lower than the lower limit value gmin of the optimum hydraulic oil temperature range G shown in FIG. Do.

  As shown in FIG. 6, the stopping device is provided in a pipe line 50 that communicates the fan pump 14 and the fan motor 23 that operates the cooling fan 22, and a pipe line 51 that communicates the tank 37, and includes an on-off valve. The pilot stop valve 43, a pilot pump 40 that is driven in synchronization with the fan pump 14, and a pilot switching valve that is provided in a pipe line 52 that communicates the pilot pump 40 and the control unit of the fan stop valve 43, and includes an on-off valve. 42 and a pilot relief valve 41 provided in a pipe line 53 that communicates a portion of the pipe line 52 upstream of the pilot switching valve 42 and the tank 37. Other configurations are the same as those of the first embodiment.

  The fan controller 35 of the second embodiment configured as described above performs a process of operating the stop device so as to stop the cooling fan 22 instead of the process of step S7 of the flowchart shown in FIG. Other processes are the same as those in the first embodiment.

  That is, in the second embodiment, when it is determined in step S6 of FIG. 5 that the hydraulic oil temperature t of the suction pipe shown in FIG. 3 is lower than the lower limit value gmin, the control signal output from the fan controller 35 is used. The pilot switching valve 42 is switched to the open position in the lower part of FIG.

  Thereby, the pilot pressure of the pilot pump 40 is guided to the control unit of the fan stop valve 43 through the pipe line 52 and the pilot switching valve 42, and the fan stop valve 43 is switched to the open position which is the left position in FIG. .

  In response to this, the conduit 50 connecting the fan pump 14 and the fan motor 23 communicates with the tank 37 via the conduit 51 and the fan stop valve 43. Accordingly, the drive of the fan motor 23 is stopped and the rotation of the cooling fan 22 is stopped.

  According to the second embodiment configured as described above, the cooling fan 22 can be stopped when it is not necessary to cool the oil cooler 20, so that unnecessary cooling of the oil cooler 20 can be prevented and energy saving can be achieved. Can be realized. Other functions and effects are the same as those of the first embodiment.

  The first and second embodiments described above are configured by a super-large hydraulic excavator. However, the present invention can be applied to a hydraulic excavator that is smaller than the super-large hydraulic excavator, and is constructed differently from the hydraulic excavator. The present invention is also applicable to machines.

2 Revolving body (main body)
DESCRIPTION OF SYMBOLS 3 Work apparatus 4a Boom cylinder 5a Arm cylinder 6a Bucket cylinder 10 Engine 11 1st hydraulic pump 12 2nd hydraulic pump 13 3rd hydraulic pump 14 Fan pump 15 Hydraulic cylinder 19 Turning motor 20 Oil cooler 21 Cooler relief valve 22 Cooling fan 23 Fan Motor 30 First temperature sensor 31 Second temperature sensor 32 Third temperature sensor 35 Fan controller 36 Inlet side pipe 37 Tank 38 pipe 40 Pilot pump 41 Pilot relief valve 42 Pilot switching valve 43 Fan stop valve 50 Pipe 51 Pipe 52 Pipe line 53 Pipe line Ne Engine speed NA, NB Cooling fan speed La Operating amount Po Discharge pressure Qp Computation pump discharge flow rate t Hydraulic oil temperature Qr Computation return flow rate Qo Computation oil cooler passage flow rate To a Oil cooler air inlet temperature G Optimal hydraulic oil temperature range gmin Lower limit value gmax Upper limit value To1 Inlet temperature To2 Outlet temperature ΔT Actual temperature difference ΔTA Temperature difference calculation value Δts Lower limit threshold value Δtm Upper limit threshold value N-Hi Maximum speed N-Lo Minimum Rotational speed

Claims (4)

A main body, a working device attached to the main body, a plurality of actuators including an actuator for operating the working device, an operating device for operating these actuators, an engine mounted on the main body, and driving by the engine A variable capacity hydraulic pump; an oil cooler that cools the return oil from the actuator; a cooling fan that generates air to cool the oil cooler; a fan motor that operates the cooling fan; and a variable that drives the fan motor In a construction machine provided with a capacity type fan pump and a cooler relief valve provided in a pipe line connecting the inlet side pipe of the oil cooler and a tank, and allowing the excess flow rate of the inlet side pipe to escape to the tank ,
A first temperature sensor that detects a hydraulic oil temperature of a suction pipe of the variable displacement hydraulic pump, a second temperature sensor that detects an inlet temperature of the oil cooler, and a third temperature sensor that detects an outlet temperature of the oil cooler;
According to the operation amount of the operating device, the rotational speed of the engine, the discharge pressure of the variable displacement hydraulic pump, the hydraulic oil temperature of the suction pipe detected by the first temperature sensor, and the rotational speed of the cooling fan, Find the temperature difference calculation value at the inlet and outlet of the oil cooler,
The inlet temperature of the oil cooler detected by the second temperature sensor when the hydraulic oil temperature of the suction pipe detected by the first temperature sensor is equal to or higher than a lower limit value of an optimum hydraulic oil temperature range set in advance. And a fan controller that calculates a measured temperature difference that is a difference between the outlet temperature of the oil cooler detected by the third temperature sensor and controls the capacity of the fan pump based on the calculation result,
The fan controller is
A first control table for setting a correlation between the hydraulic oil temperature of the suction pipe and the rotation speed of the cooling fan, a difference between the measured temperature difference and the temperature difference calculation value, and a rotation speed of the cooling fan. A second control table for setting the correlation,
The correlation set in the first control table is such that when the hydraulic oil temperature of the suction pipe is lower than the lower limit value of the optimum hydraulic oil temperature range, the number of revolutions of the cooling fan is set to the minimum discharge amount. The minimum number of rotations according to the driving state of the variable displacement hydraulic pump controlled by
When the hydraulic oil temperature of the suction pipe is higher than the upper limit value of the optimum hydraulic oil temperature range, the rotation speed of the cooling fan is kept at the maximum rotation speed,
When the hydraulic oil temperature of the suction pipe is not less than the lower limit value and not more than the upper limit value of the optimum hydraulic oil temperature range, the rotation speed of the cooling fan is gradually increased as the hydraulic oil temperature of the suction pipe increases. Consisting of changing correlations,
The correlation set in the second control table is such that when the difference between the measured temperature difference and the temperature difference calculation value is smaller than a lower limit threshold, the rotation speed of the cooling fan is maintained at the maximum rotation speed,
When the difference between the measured temperature difference and the calculated temperature difference is equal to or greater than the lower limit threshold, the rotational speed of the cooling fan is increased from the maximum speed as the difference between the measured temperature difference and the calculated temperature difference increases. The construction machine is also characterized by a gradually decreasing correlation. The construction machine according to claim 1,
The correlation calculated in the second control table is a correlation that maintains the rotation speed of the cooling fan at the minimum rotation speed when the difference between the measured temperature difference and the temperature difference calculation value is larger than an upper limit threshold. Construction machine characterized by comprising. The construction machine according to claim 1,
A stop device for stopping the rotation of the cooling fan;
The fan controller performs control to operate the stop device so as to stop the rotation speed of the cooling fan when the hydraulic oil temperature of the suction pipe is lower than the lower limit value of the optimum hydraulic oil temperature range. A featured construction machine. The construction machine according to claim 3,
The stopping device is
A pipe line connecting the fan pump and the fan motor that operates the cooling fan, a pipe line connecting the tank, and a fan stop valve comprising an on-off valve;
A pilot pump driven in synchronism with the fan pump;
A pilot switching valve that is provided in a pipe line connecting the pilot pump and the control unit of the fan stop valve, and includes an on-off valve;
And a pilot relief valve provided in a pipeline communicating with the tank and a portion of the pipeline communicating with the pilot pump and the control unit of the fan stop valve located upstream of the pilot switching valve. And construction machinery.